Telephone system



May 23, 1933- J. H. Voss l1,910,415

I' TELEPHONE SYSTEM Filed oct. 19, 1951 Teun/K *l u 1N EXCHANGE ...Jahn H. Unas Patented May 23, 1933 usura stars PATENT orion JOHN H. VOSS, OF IBERWYN, ILLINOIS, ASSIGNOR, BY MESNE 'ASSIGNMENTS TO ASSOCIATED ELECTRIC LABORATORIES, ING., OF CHICAGO, ILLINOIS, A CORPORA- TION 0F DELAWARE TELEPHONE SYSTEIJI Application led October 19, 1931. Serial No. 569,610.

This invention relates in general to telephone systems, but is more particularly concerned with small intercommunicating or private branch systems, especially of the trunk connected type, and the object of the invention, briefly stated, is the provision of new and improved circuit arrangements which are particularly suitable for use in such small systems, and which tend to reduce the cost of manufacture and installation of such systems.

One of the fea-tures of the invention relates to the means for enabling` a local subscriber to dial ring a plurality of signals common to all the local lines over a pair of common talking conductors, which are normally connected to each local line for telephone intercommunication, to code-ring a desired local subscriber by long or short rings or a combination of both.

Another feature relates to the circuit arrangements whereby each local subscriber is enabled to act in the capacity of an attendant operator to at will connect with any one of a plurality of outgoing trunk calls to originate or answer trunk calls, and to transfer such calls to another local subscriber by calling the desired subscriber over the common talking conductor and requesting such party to answer the call on a certain trunk line which is multipled between all of the local subscribers lines.

The foregoing and other features not specifically mentioned may be described more in detail by referring to the accompanying drawing` which shows by means of the usual circuit diagrams a sufficient amount of apparatus to enable the invention to be `described and understood.

In the drawing, Fig. 1 shows the equipment individual to the local subscribers lines S and S, one intercommunicating trunk or common talking line comprising conductors 4 and 5, and two interoflice trunks comprising conductors 35 to 38, inclusive, which are multipled between all the local subscribers lines over conductors 25 to 28, inclusive. The two local subscribers lines S and S, as shown, are equipped with a standard and well-known monophone telephone. Attached to the base on each standard monophone set is a subbase, such as SB shown in the dotted rec- Y tangle, having a spring assembly and keys for operating the same when making or receivingv Y base of subscriber S has three keys, one for each trunk line and a third key to enable this subscriber to disconnect all the local intercommunicating subscribers, such as S, from the trunk multiples of the interoliice trunk lines to provide secret service for subscriber S. In a system of this type only one local subscriber, preferably an executive, would be provided with a three-key sub-base while all the remaining local subscribers would be provided with a two-key sub-base, `it being understood that all the remaining local subscribers lines are multipled tothe common talking conductors 4 and 5 and the trunk multiples 25 to 28, inclusive, in the same manner as subscriber S. A push button is also provided in each sub-basev for iiashing an operator in case the trunk line terminates in a manual telephone exchange, and for cancelling dialled digits in case the trunk lines extend to an automatic telephone exchange.

lThe mechanical construction of the spring assembly and keys in the sub-bases diagrammatically illustrated in the drawing is shown in the co-pending application of H. F. Obergfell, Serial No. 536,424, filed May 11, 1931. Since the sub-bases of the subscribers lines, Such as S and S are somewhat similar, the keys and spring assemblies in the sub-base associated with subscriber S alone will be described. When the hand telephone set is removed from the cradle, springs 154 automatically close. If either key TRK 1 or key TBK #2 is depressed, the bar 161slides in a horizontal direction, and by means of bushings 162, 163, andV 164 operates springs 151, 152, 156, 157, and'158. Springs 155 are operated only when key TBK #2v is depressed. A mechanical lock (not shown) is provided for preventing either the key TBK #l or key TBK #2 from beingV operated when the other is operated.` The catch bar 160'is operated responsive to the removal of the handset from the cradle to position itself so that when springs 152 and 155 are operated the same will be mechanically locked until the hand set is replaced on the cradle irrespective of the subsequent operations of the keys. The key SS controls only springs 159. The three keys or levers are moved off center and remain in such position until moved by hand back to their normal positions or until the handset is replaced-onthe cradle, which automatically return the keys to their normal positions. rIhe push button PB controlling springs 150 is of the self-restoring type and operates the springs 154 only as -long as the push button is depressed.

Relays 11 to 14, inclusive, are provided in orderto enable the local subscribers to dial ring or operate the common call signals 21, 21-etc., which are located at various points .throughout the system. These relays are individual vto the common talking conductors 4 and 5. Associated with the two trunk lines are shown bells 42 and 43 which produce different tones when operated by ringing current from the main exchangeto enable the local subscribers to answer on the proper trunk line. In addition to this signalling arrangement, or in place thereof, alternating current relays 33 and 34 are bridged across the trunk lines and are operated by ringing current transmitted from the main exchange to light ajplurality of different colored lamps throughout the system to enable the local subscribers to answer the trunk calls on the proper trunk lines. All of the relays shown are mounted in a small terminal block while the-various signals shown are mounted at various positions throughout the establishment where the subscribers may readily hear or see such signals.V

Fig. 2 diagrammatically illustrates the manner in which a system of this type will receive its operating and talking battery. In Fig. 2, the conductors 79 and 80 connect the local commercial source to a vrectifier or battery eliminator 81, which produces the proper amount of direct current for operating and talking purposes. The rectifier or battery eliminator may be of any well-known or standard manufacture which produces the proper voltage. Incase the battery-feed is to be supplied by a rectifier or battery Veliminator the negative battery terminal 89 is connected to the rectiiier by way of the fuse, terminal 84, and terminal 83, while the positive terminal 90 is connected by way of terminal 87 and terminal 88 to rectifier 81. In case dry cells or batteries are to be used in place of a rectifier, the negative terminal 89 and positive terminal 90 are connected by way of terminals 84, 85, 86, and 87 to the battery 81. It will be understood that wherever battery is diagrammatically illustrated in Fig. lthe negative battery terminal 89 is in reality connected .toV such battery symbol.

The same is also true with respect to the positive battery terminal 90 and the various ground symbols throughout Fig. 1. Y

Talking battery is supplied from the main exchange on trunk connections while the talking battery for local connections extends through a winding of line relay 11 and ground.

Having described the equipment and appar-atus, a detailed description of the operation will now be given. For this purpose, it will vbe assumed that subscriber S desires to call subscriber S. In order to call subscriber S', subscriber S will remove the hand set fromthe cradle and dial digits 8 and 2 in order to operate the common signals 21, 21', etc., to code-ring subscriber S with one long ring followed by a short ring. Responsive to the removal of the handset from the cradle, a circuit may be traced for energizing the common line Vrelay 11 as follows: from grounded conductor 5, normally closed spring in engagement with spring 56 and said spring, conductor 3, normally closed springs 50, controlled by push button PB, conductor 1, through the substation .circuit to conductor 2, spring 51 and its normally engaged spring, conductor 4 and through the winding of line relay 11, to battery.

Subscriber S is, therefore, connected to the l common .talking conductors 4 and 5 responsive to the removal of the handset from the cradle. In response to the operation of the calling device CD for the first digit, in this VCase digit .8, the common line relay 11 is intermittently deenergized and energized in ac cordance with the number of impulses transmitted by the calling line. Upon the first .deenergization of line relay 11, said relay at armature 15 and its working contact closes an obvious circuit for energizing slow-to-release relay 12. Relay 12, upon energizing, at armature 16 prepares a circuit for energizing slow-to-release relay 13. On the first deenergization of the line relay 11, the circuit for energizing slowto-release relay 13 is completed at armature 15 and its back contact. At armature 17 relay 13 prepares a circuit for energizing slow-to-release relay 14, which is completed Von the next energization of line relay 11. It should possibly be mentioned that relays 12, 13, and 14, due to their construction, will not release between impulses. l/Vhen relay 11 reenergizes the prepared circuit for relay 14 is completed, and the latter relay at'armature 18 completes a circuit for operating the common signals 21, 21', etc., located at .different points throughout the establishment over a circuit including the connectors 19 and 2O which are connected to the commercial source of power. Since the first digit dialled is digit 8, the circuit for energizing relay 13 will be intermittently closed eight times in order to maintain relay 13 energized for a period of time equivalent to a long ring. Since relay 13 atarmature 1T controls the circuit of ringing relay 14, it 1 1. 4 will, therefore, be seen that relay 14 is maintained operated. for an interval after relay 13 deenergizes. Therefore, 1n this case, since the digit 8 was dialled, the ringing relay is maintained operated for a period which corresponds to the long ring, Vand the commen signals, therefore, 1n response to the hrst digit, are operated for one long ring. 1n response to the second digit, or digit 2, the re-` lays respond in the same manner as previouslydescribed, only in this case since only two impulses are transmittedthe ringing relay 14 will be energized for a shorter interval of time, and, therefore, the' common signals will be operated a second time in a short ring. The calling subscriber may continue to dial the code of the desired called subscriber until such party answers. Jhen subscriber S hears his code of one long and one short ring,- subscriber S will remove the handset frein the cradle and complete the desired telephone connection. The substation circuit of subscriber S", in response to the removal of the handset freni the cradle, is connected to the common con ductors 4 and 5, through the spring assembly in the same manner as explained for subscriber S. After conversation, and in respense to the replacement of the handsets n their respective cradles the circuit of line relay 11 is opened Yand said relay deenergizes, thereby deenergizing relay 12. Subscriber S can call any other local subscriber, such as S, in a manner similar to that described. The other local subscribers lines (not shown) may also complete local connections in the same manner as just described.

lt will now be assumed that subscriber S desires to originates an outgoing call over trunk No. 1. Subscriber S then removes the handset from the cradle and operates the key TBK In response to the operation of key TRK #1, bar 61 slides in a horizontal direction and operates springs 51, 52, and 56. The substation circuit is now connected to the main exchange over the following circuit: conductor 3'?, armature 70, multiple trunk conductor 27, resting contact of armature 23 and said armature, conductor @working contact of spring 51 and said spring, conductor 2, through the substation circuit, conductor 1, push-button springs 50, conductor 3, springs 56 and 58, armature 24 and its resting Contact, trunk multiple conductor 28, armature 71, and conductor 38 to the main exchange. In case trunk No. 1 extends to a manual exchange, subscriber S may operate the push-button PB to momentarily open and close the loop to signal the operator at the main exchange in the well known manner. In case trunlr No. 1 extends te an automatic exchange, the trunk conductors 37 and 38 would terminate in a lineswitch whichfis operated to automatically select the first numerical switch in the automatic exchange. Subscriber S may thereafter operate the calling device in, accordance with the directory number of the desired main exchange subscribers line to operate the automatic switches in the well-known manner to complete the connection.

ln case subscriber S desires to hold the trunk connection while completing a local connection over the common talking c0nduc ters 4 and 5 to another local subscriber in order to receive certain information, subscriber S will thereupon release the lrey TBK 1, thereby permitting the slide bar 61 to return to its normal position. W'hen slide bar 61 returns to its normal position, springs 51 and 56 alsoreturn to their normal positions and connect the substation circuit to the common talking conductors 4 and 5. Springs 52, however, are maintained in operated position by the lock catch 60 to complete a holding circuit over the trunk conductors, as follows: from armature 23, conductor 6, operated springs 52, springs 54, springs 57' and 58, to armature 24 and thence over the multiple trunk connections, as previously traced. Subscriber S then dial rings the code of the desired subscriber and this subscriber, in response to his code ring, will answer and be connected to the common talking conductors 4 and 5. After subscriber S has received the desired information subscriber S will reoperate key TRK #1 to disconnect the substation circuit from the common conductors 4 and 5 and connect the substation circuit to the trunk No. 1 over the circuit previously traced. 1t might also be stated that if the subscriber S desires another local subscriber to come in on the trunk connection, the subscriber S will complete connection with said subscribers line and tell him to operate his hey TRK #1, whereupon the second subscriber is connected to trunk No. 1 in the same manner as previously described. Sub scriber S may also return to this trunk connection by reoperating his trunk key, thereby establishing a three-party connection.

The connection of the subscribers line, such as S or S', to trunk No. 2 is somewhat similar to that described for connections to trunk No. 1, only in this case the key TRK #2 is operated to operate the slide bar 60 or 160 to operate the same spring assembly as previously operated by, the key TBK #1. In addition, the key TBK #2 operates the springs, such as springs 55 or 155 to complete the circuit for the trunk relays 22 and 30 in the respective subscribers trunk line circuits. lt Will be noted that both springs 55 and 155, when operated, are locked in operated position by the locking bars 66 and 160 until the handset is replaced on the cradle. It will be noted that trunk No. 1 is normally connected to the spring assembly in the sub-base by Way of resting contacts on relays 22 andl 30',- and that trunk No. 2 terminates in Working contacts of such relays. Therefore7 When the relays, such as relays 22 and 30, are energized by key 'IRK #2 the connections to trunk No. 1 are opened and the trunk No. 2 is connected to the various spring assemblies. Vith the above description, it is believed' that it Will be yunnecessary to explain the detailed connections forconneoting the local subscribers lines to trunk No. 2, because such connections are the sameas previously described With the exception of the operation of relays such as 22 and 30 to select trunk No. 2.

It will now be assumed that a main exchange subscriber' desires to converse With one of the local subscribers, and in the course of establishing a connection said main exchange subscribers line has been connected to trunk No. 1, terminating in conductors 37 and 38. `When trunk No. 1 is seized at the main exchange, the connector switchv thereat transmits ringing current over conductors 37 and 38 in the Well-known manner. As previously stated, trunk No. 1 may be equipped with a number of multiple ringers, such as 42, which are located at different points throughout the establishment, or may be provided with an alternating current relay, such as 33, which closes an obvious circuit for lighting the lamps, such as lamp 41, which are located at different points visible to the klocal subscribers throughout 'the establishment. Therefore, in response tof ringing current, the multiple bells 42 or the colored lamps 41.are lighted to indicate an incoming trunk' call. Since there are two trunk lines, the local subscriber must b e able to distinguish Which trunk line the incoming' call is on, and, therefore', the multiple bells 42 are of one tone and the lamps 41 are of a certainA color in order t0 designate trunk No. 1. Any local subscriber in response to the operation of the incoming tru-nk signal kmay operate key TBK #l and complete connection to such trunk line by the operation of the spring assemblyk in the same manner asdescribed for outgoingcalls. In case the incoming call arrives over trunk No. 2', then the multiple bells 43, preferably'of a different tone from the bells 42 of trunk \To. 1, or'the alternating current relays 34 are operated in response to ringing current transmitted from the main exchange. The relay 34, when' operated, Will close an obvious circuit for operating the lamps 40, Which are of a different color from the lamps 41 associatedwith trunk No. 1. In responseV to the operation'of the signals associated with trunk No. 2, any local subscriber may answer the trunk call by the operation of key TBK #2. By the operation of key TBK :tft-2, relays, such as relays 22 or 30, ivill be operated to connect the subscribers line to trunk line No. 2. The local subscriber can hold this trunk line and transfer the call to another local subscriber in the same manner as previously described. In' this system it is, therefore, obvious that there may be as many las threey simultaneous connections, that is, there may bei one local connection over the common talking conductors, and tWo trunk connections in progress at the' same time.

' In a system. of this kind, it may happen'. that theexecutivei may Wish to talk overl onel of the trunk lines Without danger of any of the other local subscribers overhearing that conversation. The' key SS andV springs 159v for controlling relays 31 and 32 are provided for this purpose. If the executive desires to hold a secret conversation over the mainexchangetrunk line When connected there'- to, he will then operate the key S'S to close springs 159 to operate either relay 31er 32, dependent upon the trunk line which at this time is connected to the executives substation circuit. In case the trunk No. 1 is at' this time connected to the executives su-bstation circuit, then relay 32 Vis-opera-ted from ground at springs 159, armature 46 and its resting contact, and through the Winding of relay 32, to battery. Relay 32, upon energizing, at armatures and 71 discon` nects the trunk multiples 27 and 28 from the trunk conductors 37 and38 to prevent any other local subscriber from` overbearing the conversation. In case the' executive Was talking vover trunk No. 2 instead of trunk No. 1, the operation-of key S-S completes a` circuit for energizing relay 31 instead of' relay 32 because atthis time relav 30" would have been energized in response to theoperation of key TRK #2. By the operation of relay 31, said relay at armatures 48 and 49 disconnects the trunk multiples 25 and 26 froml the trunk conductors 35S-'andV 36 to i" prevent any of the other local subscribers from overhearing the conversation.

In order to provide con-ference callingI in a system' of this type, it is only necessary that some prearranged code signal, designating a.- conference call for certain subscribers, be dialed to operate the common signals 21,21', etc., whereupon all ofthe local subscribers desired in conference Will re-` move their receivers and be connected to the common'conductors 4 and' 5.

Having described the invention, what is desired to be protected by Letters Patent will be set forth in the following claims.`

l/Vhat is claimed is:

' 1. In a local intercommunicating telephone exchange, a plurality of local subscribers lines, a pair of talking conductors normally connecting all the local lines together for local telephone'service, a plurality of signals common to all said lines, a plurality of trunk lines multipled to all said subscribers lines but normally disconnected therefrom, and subscriber controlled means for operating' said common signals over said common conrre duct-ors, for completing a local telephone connection between said local lines over said common talking conductors, for answering a trunk call over any one of said trunk lines, and for initiating a trunk call over any desired one of said trunk lines.

2. In a local intercommunicating telephone exchange, a plurality of local subscribers lines, a pair pf talking conductors normally connecting all the local lines together for local telephone service, aplurality of sig4 nals common to all said lines, a plurality of trunk lines multipled to all said subscribers lines but normally disconnected therefrom, and subscriber controlled means for operating said common signals over said common conductors, for completing a local telephone connection between said local lines over said common talking conductors, for answering a trunk call over any one of said trunk lines, for initiating a trunk call over any desired one of said trunk lines, and for holding a trunk line while making a local connection.

3. In local intercommunicating telephone n exchange, a plurality of local subscribers lines. a pair of talking conductors normally connecting all the local lines together for local telephone service, a. plurality of signals common to all said lines, a plurality of trunk lines multipled to all said subscribers lines but normal disconnected therefrom, subscriber controlled means for operating said common signals -over said common conductors, for completing a local telephone connection between said local lines over said common talking conductors, for answering a trunk call over any one of said trunk lines, and for initiating a trunk call over any desired one of said trunk lines, and a rectilie-r connected to a local source of alternating current for producing direct current to provide operating and talking battery to said lines.

4. In a local telephone system, a plurality of local subscribers lines, a common talking circuit including` only a pair of talking conductors norm-any connecting all said lines for telephone communication, a plurality of signals common to said lines for indicating a call in progress when operated, and means controlled by each subscriber for code ringing the desired one of said lines by simultaneously operating all said commonr signals over said pair of talking conductors in accordance with the code signal assigned to the desired line. y

5. vIn a local telephone system, a plurality of local subscribers lines, a common talking circuit normally connecting all saidlines for telephone intercommunication, a plurality of signals common to all said lines, means individual to each line for transmitting a plurality of series of impulses over said common talking circuit, all said common signals simultaneously and continuously operated for the duration of `each series of impulses transmitted to code ring a desired subscriber.

6. In a local intercommunicating telephone system, a plurality of` local'subscribers lines, a common talking circuit normally connecting said lines for intercommunicatiom a calling device individual to' each line for transmitting a long or a short series of impulses over said talking circuit dependent upon the value 0f the digit dialled, and a plurality of signals common to all said lines and operated once for each transmitted series of impulses to code ring a. desired subscriber by a combination ring in accordance-with the value of the digits dialled 4 A ,7. In a telephone system, a plurality of subscribers lines each including a substation circuit, a pair of talking conductors common c to all said subscribers lines, switchhook springs in each substation circuit operated responsive to the removal of the receiver thereat for directly connecting the substation circuit to said common talking conductors, a calling device individual to each substation circuit for transmitting a long or a. short series of impulses over said common conductors dependent upon the value kofthe digit dialled on the opera-tion of the calling device, and a plurality of signals common to all said lines operated inresponse to each operation of the calling device to codering a desired subscriber by a combination v.of short or long rings or both dependent upon the value or the digits dialled on successive operations ofthe calling device. 1 f 8. In a telephone system, a local exchang anda distant exchange, a plurality of subscribers lines in said local exchange, a common talking circuit normally connecting all said subscribers linesfor local communication within the local exchange, a plurality of signals common to all said subscribers lines, a plurality of trunk lines connecting the local exchange with said distant exchange, said trunk lines common to all said subscribers lines but normally disconnected therefrom, means individual to each subscribers line for enabling the subscriber thereat to disconnect his line from said common talking circuit and connect his line to any desired one of said trunk lines, for enabling the subscriber to thereafter disconnect his line from' said trunk line and connect his line to said common talking circuit without releasing said trunk line, means cont-rolled by said subscriber for dial ringing said common signals over said common talking circuit to code ring a desired subscriber, means responsive to the desired called subscribers answering from any local subscribers line'for connecting this subscribers line to said common talking circuit to Vcomplete a local talking circuit between the two subscribers to enable the lirst subscriber to tell the second subscriber that he is wanted on a certain trunk line,;and.said individual means at theanswerers lines, a pair olf-springs individual to said ing subscribers line operated .by the called subscriber :to disconnect said answering subscribers line frein-said common talking circu-it and `connect such .line vto the held ltrunk line to complete the connection rdesi-red on said vtrunk line.

l9. In a telephone system, a local exchange and a distant exchange, a plurality of subscribers lines in said local exchange, ya commontalking circuit provided or local telephone communication 'between subscribers within ythe local exchange, ,switching means individual to each -subscribers line for normally connecting said common talking circuit Ato peach subscribers line, a plurality of trunk `lines 'connecting the local exchange :sa-id distant exchange, said trunk lines terminating in each individual switching means fbut normally ydisconnected from the subscribers lines, :a key individual to each trunk'rline yat each subscribers line for controlling Isaid switching means, the individual switch-ing means at any Aone of said subscribers lines, operated responsive =to the operation of any one of said individual keys thereat elfor disconnecting said subscribers line :from said common talking circuit .and Yttor connecting vsaid subscribers line to the trunk line corresponding to the operated key, sa-id switching means operated responsive to the restoration of said operated 'key for providing ka holding v'circuit :Eo'r said ftrunk line, for disconnecting said subscribers line from said trunk line and ffor connectingrsaid subscribers 'line to said cominontailking circuit incasesome 'other subscriber is desired fon said trunk line, signaxlsicommonto allsaidflocalsubscribersflines, meansVcontrolledby-saidfsubscriberort-ransmitting fa Vplurality cofseries kof impulses over said commontalking circuittozcode ringsaid common signals in=accordance with the duration ozf'each series transmitted land in accordance with the code .ring of the desired other subscriber, means responsive xto the called subscribers answering at any local subscriberis )line Lor connecting this subscribers line to .said common talking circuit to acomplete :a talking .circuit between ythe two subscribers to enable :the iirst subscriber to =tell the called .subscriber that he :is wanted l'on a certain trunk ;line,=and the individualswitching means at :said secondsubscribefs Aline loperated responsive to the operation ott fthe proper tnunkkey Vfor disconnecting the .second subscribers line :fromsa-id common talking circuit fand Vfor connecting the second subscriber?s Yline to `the held trunk line 'tofcomplete the desired connection over ysaid trunk ine. Y

l10.*In a :telephone system, a isubscribers line, other subscribers lines, a .pair 'of 'talking conductors normally connecting said subscribers lime with ail of :said othersubscribline and controlled by'said subscriber, a plurality of trunk lines, means responsive to a call bythe subscriber on said line and the operation of said springs vfor establishing a connection between said .-subscribers line-and one lof -said trunk lines, means for locking said :springs 'in 'operated position, a lholding circuit including said springs ffor lholding :an established trunk connection Vover any of said trunk lines, and means for establishing said holding circuit while completing .a local talkingconnectionoversaid vpair of `com-mon talking conductors tosaid other subscribers lines.

ll. In a telephone system, asubscribers line, sets of springs individual to said line, 1a. firstrand a second trunk key controlled by said Vsubscriber for controlling said springs, .a

trunk fline `.circuit individual 4to said line .and

connected rto said springs, a iii-st zand asecond trunk iline terminating in said individual trunk line circuit, means responsive to the operation of'either :key and said springs by the subscriber for establishing a vconnection between said subscribers line and the trunk line corresponding to the 4operated key by way of said trunk line circuit, means for automatically locking a--certain-set off-said springs in response to vtheir initial operatioma holdingcircuit including said-certainse't yof :locked lish said holding circuit, and means for u-nlocking said certain set-ef springs responsive to the replacement kof the receiver vby the subscriber.

12. In a telephone system, .a plurality 'of local subscribers lines, sets :of springs indii v idual to and .terminatingeach subscribers line, ya pair of common talking conductors normally connected to each subscribers line by way ofsaid' sets of springs, a trunk line circuit individual 4to each Asubscribers line and terminating in said individual sets of springs, -afirst and a second trunk fline each terminating in each individual trunk -line circuit, a corresponding first andsecond trunk line key individual to =each subscribers line for controlling-the individual fsets `of springs, means responsive to the operation of .either key and said springs at-one of said -subscribers lines Afor -disconnecting ysaid subscribers line from said normally connected common talking .conductors and for establishing a connection between said subscribers line and the trunk line corresponding to the operated key bjy way ofthe associated individual .trunk line circuit, meansior automatically 'lockinga certain set of said individual operated .springs in response to their initial operation by either of said keys, a holding circuit for each subscribers line including Asaid certain set of locked springs for holding an established AEl) trunk line-connection, means responsive to the restoration of the operated key for restoring all said operated springs except said locked springs to establish said holding circuit, and means for unlocking said certain locked set of springs responsive to the replacement of the receiver by the subscriber.

13. In a telephone system, a plurality of local subscribers lines, sets of springs individual 'to and terminating each subscribers line, a pair or common talking conductors normally connected to each subscribers line by Way of said sets of springs, a trunk line circuit individual to each subscribers line and terminating in said individual sets of springs, a first and a second trunk line each terminatinOr in each individual trunk line circuit, a corresponding tirst and second trunk line key individual to each subscribers line for controlling the individual sets of springs, means responsive to the operation of either key and said springs at one of said subscribers lines for disconnecting said subscribers line from said normally connected common talking conductors and tor establishing a connection between said subscribers line and the trunk line corresponding to the operated key by Way of the associated individual trunk line circuit, means for automatically locking` a certain set of said individual operate( springs in response to their initial operation by either of said keys, a holding circuit for cach subscribers line including said certain set oi locked springs for holdingan established trunk line connection, means responsive to the restoration of the operated key for restoring all said operated springs eXcept said locked springs to establish said holding?,` circuit, means for unlocking said certain locked set of springs responsive to the replacement ot the receiver by the subscriber, means responsive to the restoration of the operated key for restoring` all said operated springs except said locked springs to establish the holding circuit for said connected trunk line and to reconnect the subscribers line With said common talking conductors, a set of signals common to all said subscribers lines, means controlled by said subscriber for transmitting a plurality of series of impulses over said common talking conductors to operate said common signals to code ring a desired subscriber in accordance With the length of each impulse series, means responsive to the called subscriber answering for completing a talking circuit over said common talkingconductors and the individual spring sets and the calling and called subscribers lines, and means whereby either subscriber by the operation of the trunk key corresponding to the held trunk line may operate their individual spring sets to connect their lines with the said held trunk line by Way of their individual trunk line circuits.

14. 1n a telephone system, local subscribers lines each comprising a local line circuit normally connected to each other over a pair of common talking conductors', a trunk line circuit, a substation circuit, a spring assembly for connecting the substation circuit to either the trunk line circuit or the local line circuit, and a first and second trunk key for controlling said spring assembly, a plurality or" tu -Way intereXch-ange trunk lines terminating in each trunk line circuit, means responsive to the operation of the lirst trunk key at one of the subscribers lines for operating the spring` assembly thereat and for connecting the subscribers substation circuit to the lirst of said trunk lines by Way of the associated trunk line circuit ymeans responsive to the operation of the second trunk key at id subscribei"s line for operating said sping assembly thereatand for connecting the subscribers substation circuit to the second trunk line by Way of said associated trunk line circuit, and a holding circuit included in said spring assembly for holding a trunk connection by Way of said trunk line circuit when an operated trunk key is restored to normal.

15. ln a telephone system, local subscribers lines each comprising a trunk line circuit, a substation circuit, a spring assembly for connecting the substation circuit to the trunk line circuit, and a pair of keys either one of which controls the opeation oitsaid spring assembly, a pair oil common talking conductors normally connecting all the subst-ation circuits of all the subs rib-ers lines to each other by Way of said spring assemblies, a relay having normally open and normally closed contacts in each trunk line circuit, a lirst trunk line multipled between said trunk line circuits and connected to each spring assembly b way of said normally closed contacts on said relays, a second trunk line multipled between said trunk line circuits and connected to said normally open contacts on said relays, means for establishing local telephone connections between said local lines over said pair of common talking conductors and the associated spring assemblies, means for disconnecting said substation circuits from said pair oi common talking conductors and for connecting the substation circuits to their associated trunk line circuits in response to the operation of either of said associated keys, and means `tor operating the relay of the associated trunk line circuit only in case a certain one of said keys is operated to connect said second trunk line to the substation circuits by Way of said normally open contacts and said spring assembly in place of said lirst trunk line,

15. In a local intercommunicating televphone exchange, -a plurality of local subscribers lines and a local executives line, a trunk line circuit individual to eachV of said lines but normally disconnected therejnrom, a plurality :of .tnimli lines extending from a distant exchange terminating lin the executivels :trunk line circuit, a multiple connection for ,ea ch otsaid trunk lines connecting `the trunk line circuits of each osaid plurality of lines with-the trunk line circuit .of ysaid fcxecutives l-ine, `connecting means inthe executives trunk line circuit normally connecting said .multiple connections to their respective .trunir lines, subsc: 1i-ber controlled means individual to each of said plurality of subscribers lines Jfor connecting such lines at Wil-l to any desired one of said tru-nk lines by way :of theirtrunlr line .circu-itssaid multiple connections, land ksaid connecting means, -subscribe-r controlled means individual to said executives line for connecting said li-ne at will to -any desired one of said trunk lines by Way of its trunk line circuit, and additional subscriber controlled kmeans at only the executines line for operating said connecting means to disconnect any desired one of said ltrunk lines from its associated multiple connections at lthe ivi-ll of tbe executive.

'1.7. In a local .intercommunicating telephone exchange` a plurality of local subscribers lines and a local enecutives line, Aa. trunk line ci-rcnit individual vto each o said lines but normally disconnected therefrom, a plurality of trunk lines extending from a distant exchange terminating -in fthe eXecutives taunk line circuit. a multiple connection for each of said 'trunk lines connecting the trunk line .circuits of each of said plurality of lines .with the trunk line circuit'of'sa-id eXecuti-ves li-Inc, .connecting means in the `execntives trunk -line circuit normally connecting said .multiple connections to their :respective trunk lines, a trunlkey for each of said trunk'lines at yeach ot said plurality of subscribers and eXecutives lines, means Vresponsive Ito the operationot a. trunk-key at vany one of said pluvita'lity of subscribers"1ines Jor connecting such lines to `the trunk line corresponding to the operated trunk key by Way oftheir individual .trunk line circuits, the corresponding trunk multiple connections, and said connecting means. means responsive to the operation of a .trunk key at said executives line for connecting such line `tothe trunk 'line corresponding to the operated trunk 'key by Way of the executives individual trunk line circuit, vand a special key on only saidexecutives line for operating said connecting means `to disconnect but one of said trunk lines at a time from -itssaid trunk multiple connections, the particular one trunk linebeing disconnected from its multiple connections 'by-the operation ot said connecting means 'being dependent upon which one of said trunk 'keys is operated atp-the executives line. f

18. In a telephone system, local subscribers lines and an eXecutives Yline each comprising a substation circuit' and Va trunk line circuit,

i aapai'r oflcommonftalkingconductors, a spring .assembly individual to each line Vnormally .ccnnectingall fthesubstation circuits together over said common talkingconductors and for .operatively connecting said substation circuits .tothe trunk line circuits, a zrst :and :a second trunk liey individual to eacb line for controlling said spring assembly, a irst and a 1second trunk line :terminati-ng in .the execu- .tives trunk 4line circuit, multiple connections for each trunk line .connecting all the local trunlt line circuits to the eXecutives trunk line circuit, connecting means insa-id execu- Ati-ves trunk line circuit normally connecting said multiple trunkconnections to their respective trunk lines, means responsive tothe operation of either one of -said trunk-keys at said localor-executives lines for operating said spring assembly thereatto disconnect the substation circuit from said common talking conductors and vfor connecting the substation circuit to the trunk line corresponding to the operated-trunlckey -by Way of said trunk line circuit, said multiple trunk connections, and said connecting means, and a third key at said eXecuti-ves line for operating said connecting means to disconnect but one trunk lino at a `time from its associated trunk multiple connections, the particular trunkline being disconnected 'from its multipleconnection-sfby the operation of said connecting means being dependent .upon which one of said trunk key-s is operated'at the executives line.

1n Witness lwhereof, I hereunto subscribe my name this 15th day of October, A. D.

JOHN H. VOSS. f 

